The need for effective herbicides needs no special emphasis. The control of weeds and undesirable vegetation is of great economic importance since weed competition inhibits the production of foliage, fruit or seed of agricultural crops. The presence of weeds can reduce harvesting efficiency and the quality of the harvested crop. Weeds on noncropped areas may cause a fire hazard, undesirable drifting of sand or snow, and/or irritation to persons with allergies. Thus, suppression of undesirable weed growth is very advantageous.
Accordingly, it is an object of this invention to provide effective novel herbicidal compounds, as well as to provide novel herbicidal compositions and novel methods of controlling weeds. Further, it is an object of this invention to provide intermediates which, as well as exhibiting herbicidal activity, are also useful in the production of other herbicidally active compounds.
While certain hydroxybenzyl-substituted nitrogen-containing heteroaryl compounds are disclosed in the art, these disclosures contain no description of the utility of such compounds. Thus, Radinov et al., "Synthesis of 4-Amino-3-pyridinyl and 4-Amino-5-pyrimidinyl Aryl Ketones and Related Compounds via an ortho-Lithiation Reaction", Synthesis, pp. 886-891 (November 1986), disclose inter alia at page 887, compounds of the formula ##STR2## wherein A is CH or N, and when A is CH, X.sup.1 is H and X.sup.2 is hydrogen, chlorine or fluorine, and when A is N, X.sup.1 is chlorine and X.sup.2 is hydrogen.
Somewhat similarly, Marsais et al., "Directed Lithiation of 4-Halopyridines: Chemoselectivity, Regioselectivity and Application to Synthesis", J Heterocyclic Chem., Vol 25, pp. 81-87 (1987), disclose the production of compounds of the formula ##STR3## wherein El is phenyl or 2-methoxyphenyl.
Certain (non-substituted)-pyridyl-3-carbinols of the formula ##STR4## are disclosed in U.S. Pat. No. 4,407,806 to Cherpeck (wherein R and R.sup.1 are as defined therein).
Similarly, U.S. Pat. No. 4,116,665 to Krumkalns discloses a method of regulating the growth of aquatic weeds employing compounds of the formula ##STR5## wherein, inter alia, R.sup.1 may be hydrogen, R.sup.2 may be (substituted)-phenyl and X may be hydroxyl or alkoxy.
Further, commonly owned U.S. Pat. No. 5,308,826, describes herbicidal 4-substituted pyridyl-3-carbinols.